American Chemical Society
ic034434h_si_002.cif (117.82 kB)

A Phosphorus Supported Multisite Coordinating Tris Hydrazone P(S)[N(Me)NCHC6H4-o-OH]3 as an Efficient Ligand for the Assembly of Trinuclear Metal Complexes:  Synthesis, Structure, and Magnetism

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posted on 2003-08-20, 00:00 authored by Vadapalli Chandrasekhar, Ramachandran Azhakar, Gurusamy Thanagavelu Senthil Andavan, Venkatasubbaiah Krishnan, Stefano Zacchini, Jamie F. Bickley, Alexander Steiner, Raymond J. Butcher, Paul Kögerler
A phosphorus supported multisite coordinating ligand P(S)[N(Me)NCHC6H4-o-OH]3 (2) was prepared by the condensation of the phosphorus tris hydrazide P(S)[N(Me)NH2]3 (1) with o-hydroxybenzaldehyde. The reaction of 2 with M(OAc)2·xH2O (M = Mn, Co, Ni, x = 4; M = Zn, x = 2) afforded neutral trinuclear complexes {P(S)[N(Me)NCHC6H4-o-O]3}2M3 [M = Mn (3), Co (4), Ni (5), and Zn (6)]. The X-ray crystal structures of compounds 26 have been determined. The structures of 36 reveal that the trinculear metal assemblies are nearly linear. The two terminal metal ions in a given assembly have an N3O3 ligand environment in a distorted octahedral geometry while the central metal ion has an O6 ligand environment also in a slightly distorted octahedral geometry. In all the complexes, ligand 2 coordinates to the metal ions through three imino nitrogens and three phenolate oxygens; the latter act as bridging ligands to connect the terminal and central metal ions. The compounds 26 also show intermolecular CH···SP contacts in the solid-state which lead to the formation of polymeric supramolecular architectures. The observed magnetic data for the (s = 5/2)3 L2(Mn(II))3 derivative, 3, show an antiferromagnetic nearest- and next-nearest-neighbor exchange (J = −4.0 K and J = −0.15 K; using the spin Hamiltonian ĤHDvV = −2J(Ŝ1Ŝ2 + Ŝ2Ŝ3) − 2JŜ1Ŝ3). In contrast, the (s = 1)3 L2(Ni(II))3 derivative, 5, displays ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor exchange interactions (J = 4.43 K and J = −0.28 K; Ĥ = ĤHDvV+ Ŝ1DŜ1 + Ŝ2DŜ2+ Ŝ3DŜ3). The magnetic behavior of the L2(Co(II))3 derivative, 4, reveals only antiferromagnetic exchange analogous to 3 (J = −4.5, J = −1.4; same Hamiltonian as for 3).